In recent years, in maintenances of an FA (Factory Automation) system, systems that even inexperienced engineers can easily perform an abnormality diagnosis have been desired. However, in many cases, the FA system has a hierarchical structure in which a plurality of networks are combined together, and connection setting involved in an abnormality diagnosis and knowledge required for the abnormality diagnosis are complicated.
As a system in which a PLC (Programmable Logic Controller: sequencer) or the like is its system constituent element, there have been disclosed techniques such as: a distributed control system that regards one of PLCs connected to each other via a network as a setting-information transmitting station and holds frame configuration data also from a handy tool by a memory card (see Patent Literature 1); an abnormality diagnostic system that connects a computer to a PLC, automatically detects an abnormal state of a production facility, and provides related instruction information to a user (see Patent Literature 2); and an apparatus that displays all unit devices of a sequence control device in a tree arrangement so as to display fault information for each device (see Patent Literature 3).